Stroke is the leading cause of disability in the United States, causing motor impairments that compromise quality of life. Hemiparesis is the primary impairment underlying stroke disability and the most frequent impairment treated, yet conventional stroke rehabilitation is often unsuccessful. The efficacy of Complementary and alternative medicine (CAM) techniques in stroke is yet to be extensively examined. Moreover, although > 4 million chronic stroke patients reside in the United States, little is known about efficacious motor therapy regimens for this population using either conventional or CAM techniques. Mental practice (MP), a CAM mind-body technique in which physical skills are cognitively rehearsed, increases motor skill learning and performance. The same neural and muscular structures are activated during MP as during physical practice of the same skill. Data from this laboratory suggest that MP reduces stroke-induced hemiparesis significantly more than conventional motor therapy. However, MP mechanisms of action and optimal MP dosing are unknown and require identification before a large MP clinical trial can be performed. Study aims are: (1) To determine the dose-response relationship between MP duration and motor outcomes; and (2) to determine the MP mechanisms of action using functional magnetic resonance imaging (fMRI). Planning would include development and refinement of MP and fMRI protocols and inservicing of rehabilitation personnel. This would be followed by a multiple baseline study of motor and neural effects of 30, 60 and 120-minute daily MP doses in 33 chronic stroke patients. [11 additional patients will receive motor therapy only with no MP.] Outcome measures would include the FugI-Meyer Assessment, the Action Research Arm Test, the Wolf Motor Function Test, and the Stroke Impact Scale, as well as qualitative measures, fMRI will examine possible MP-induced cortical reorganizations. The proposed study meets NCCAM and R21 priorities, including (1) refinement of promising CAM interventions; (2) study of mind-body interactions and application of CAM techniques to cardiovascular diseases, including stroke; and (3) elucidation of CAM mechanisms of action. Identification of MP mechanisms of action and optimal dosing is fundamental to cost-effective, appropriate implementation of this promising, CAM, mind-body technique, and will enable a subsequent MP clinical trial.